ABSTRACT: This paper presents the Web decision support system for surface irrigation design, an Internet application to assist designers and managers in the process of design and planning improvements in farm surface irrigation systems – furrow, basin and border irrigation. It includes a database, simulation models, user-friendly interfaces and multicriteria analysis models. The system was developed from a stand-alone application and includes two modular components: a Web application and the simulation engine. The development applies the Framework .Net of Microsoft, with the reuse of stand-alone version source-code. The operational and simulation databases apply the SQLServer allowing a simultaneously connection of several users. This approach results on a better service quality, avoiding package installation and is more versatile to upgrade and to integrate other data and models, particularly in world water scarcity areas less developed and with major water scarcity. It is presented the application design, the logical dynamic structure and interface details.

INTRODUCTION: A decision support system was developed to assist designers and managers in the process of design and planning improvements in farm surface irrigation systems – furrow, basin and border irrigation, entitled SADREG. It allows creating a large set of alternative solutions, their impact evaluation and multicriteria selection analysis through an integrated framework of user knowledge, database and simulation models. This DSS was applied to several agricultural, economical and environmental conditions, considering several irrigation methods, equipments and practices:to optimize irrigation performance on the Lower Mondego Valley, Portugal (GONÇALVES & PEREIRA, 1999), to improve basin irrigation for water savings and salinization control, in the Upper Yellow River Basin, China (GONÇALVES et al. 2003), to improved furrow irrigation in Fergana Valley, Aral Sea Basin, Uzbekistan (GONÇALVES et al., 2005), and to modernize furrows and border irrigation in Euphrates Basin, Syria (DAROUICH et al. 2007; GONÇALVES et al. 2008).

This development of DSS for Web allows better application flexibility, improving the user support to database access and enlarging the number of users, particularly in the world areas where the water scarcity demand a better use of irrigation water. The application version here presented comprises a Web and a simulation engine module, which includes the models integrated in SADREG. This development was based on the Microsoft Framework .Net and the SQLServer to manage databases, allowing a simultaneously connection of several users.

An Internet application has a larger flexibility, with more users worldwide, including areas where the surface irrigation requires improvements and the expert technical support is more incipient. The Web access of DSS allows an easier way to transfer knowledge and tools to improve the procedures to evaluate and design the field irrigation problems. The DSS location on a server allows sharing data and comparison of results of different users. Some examples of Web applications in the irrigation subject demonstrate its usefulness (BRANCO et al., 2005; THYSEN & DETLEFSEN, 2006).

The objective of this paper is to present the Internet application of SADREG, describing the software strategy and its procedures to design, maintain and users support.